extra ply附加层extraadj.额外的n.额外之物；临时演员adv.特别地extramarital sex relation婚外性关系extrapolation coefficient外推系数extrachromosomal nucleoli染色体外核仁extra-light flint glass特轻火石玻璃extra-curricular sports课外体育extravascular enhancement血管外增强Extracorporeal circulatio体外循环extracorporal circulation体外循环extracorporeal lithoclast体外碎石机extrachromosomal genetics染色体外遗传学